A federal regulator says it will have to take further action to address mortgage approvals by Canadian banks that still depend too much on the amount of equity in a home, and not enough on whether loans can actually be paid back.

The Office of the Superintendent of Financial Institutions telegraphed the move in an update released Monday on the effectiveness of new underwriting rules it announced last year. Those rules included a new “stress test” for uninsured mortgages, where a borrower makes a down payment of 20 per cent or more.

According to OSFI’s October newsletter, the tweaks were needed after the regulator identified possible trouble spots caused by high levels of household debt and “imbalances” in some real estate markets that could have added more risk for banks.

There have been improvements in the quality of new mortgage loans since the revised B-20 guidelines came into effect this past January, OSFI says, “including higher average credit scores and lower average loan-to-value at mortgage origination.”

But even though OSFI said the new rules “are having the desired effect of helping to keep Canada’s financial system strong and resilient,” the regulator claims more work is needed.

“Although reduced, there continues to be evidence of mortgage approvals that over rely on the equity in the property (at the expense of assessing the borrower’s ability to repay the loan),” the newsletter said. “OSFI will be taking steps to ensure this sort of equity lending ceases.”

OSFI spokeswoman Annik Faucher told the Financial Post in an email that the regulator was referring to uninsured mortgages that were granted based only on the equity of the property — the difference between a property’s value and the amount remaining on a borrower’s mortgage for the property — as well as loans where the lender did not necessarily apply the other “prudent underwriting principles” laid out in the B-20 guideline, such as those aimed at proper documentation of income.

“Sound underwriting helps protect lenders and borrowers and supports financial system resilience,” Faucher said. “Having a larger amount of equity in a property does not mean sound underwriting practices and borrower due diligence do not apply.”

She added that OSFI “has a number of tools in its supervisory toolkit, and when we identify potential issues, we intervene and require financial institutions to implement remedial measures that are commensurate to the risk profile of the institution.”

OSFI said in its October newsletter that there are signs “that fewer mortgages are being approved for highly indebted or over-leveraged individuals.” According to the regulator, the amount of uninsured mortgage originations with loan amounts greater than 4.5 times the borrower’s income has dropped from 20 per cent from April to July of 2017 to 14 per cent for the same period of 2018.

In general, the Canadian housing market has cooled following intervention by regulators and various governments. But OSFI also said it realizes that its tighter underwriting rules might cause some would-be homeowners to use less-than-truthful means to obtain mortgages.

“OSFI recognizes that tightened underwriting standards may increase the incentive for some borrowers to misrepresent their income, while it has also become easier to create authentic-looking false documents,” the newsletter said. “Given that the revised B-20 calls for more consistent application of income verification processes, financial institutions need to be even more vigilant in their efforts to detect and prevent income misrepresentation. This is particularly important for financial institutions that depend on third-party distribution channels.”